Codebase Navigator Skill

Purpose

Enable faster repository comprehension and safer code modifications by systematically exploring architecture, ownership, and key documentation before making changes.

When to Use

• Starting work in an unfamiliar codebase
• Planning significant refactoring
• Before making architectural changes
• Investigating bug root causes
• Onboarding new team members

Process

1. Initial Exploration

Read in this order:

1. README.md - Project overview
2. CONTRIBUTING.md - Development guidelines
3. CODEOWNERS - Ownership and expertise
4. docs/architecture - System design
5. docs/ADRs - Architecture Decision Records

2. Map Project Structure

• Identify entry points (main.ts, index.js, app.py)
• Map module boundaries
• Document data flow
• List external dependencies

3. Find Related Code

Use scripts/find_symbols.sh to locate:

• Function/class definitions
• Import statements
• Usage sites

4. Impact Analysis

Use scripts/impact_map.py to map:

• What depends on this module?
• What does this module depend on?
• Potential blast radius of changes

Scripts

find_symbols.sh

# Find all uses of a symbol
./find_symbols.sh "ClassName"
./find_symbols.sh "functionName"

impact_map.py

# Generate dependency graph
python impact_map.py --module src/auth
# Output: Visual dependency map + affected files

Output Format

Navigator generates a structured exploration report:

# Codebase Navigation Report

## Project Overview
- **Name**: my-project
- **Type**: fullstack (React + Node.js)
- **Entry Points**: src/index.tsx, server/app.ts

## Architecture
- **Pattern**: Layered (UI → Services → Data)
- **Key Modules**: auth, api, database, ui/components

## Ownership
- **auth/**: @security-team
- **api/**: @backend-team
- **ui/**: @frontend-team

## Dependencies
- React 18
- Express 4
- PostgreSQL 14

## Impact Analysis (for proposed change)
- **Direct dependencies**: 3 modules
- **Indirect dependencies**: 12 files
- **Test coverage**: 87%
- **Risk level**: Medium

Safety Checks

Before proposing changes:

1. ✅ Read CODEOWNERS for affected files
2. ✅ Check test coverage
3. ✅ Map all dependencies
4. ✅ Identify breaking changes
5. ✅ Plan rollback strategy

Integration

Use before major operations:

• Refactoring: Map dependencies first
• Feature addition: Understand architecture
• Bug fixing: Trace execution path
• Code review: Verify impact

Codebase Navigator v1.0.0 - Explore before you code